This invention relates generally to the art of sintering and more particularly to the art of sintering boron for use as a vacuum arc cathode.
Conventionally metals have been applied as thin films by the use of vacuum arc deposition utilizing the desired metal as the cathode. Recently, attempts have been made to extend this technique to non-metals, boron in particular. Conventionally, consolidated boron available for such cathodes has been prepared by hot pressing of boron powders to form a disk which is subsequently used in the cathodic (vacuum) arc evaporation technique. It has been found that such cathodes are extremely short lived because of the severe stresses interposed by this technique.
Vacuum cathodic arc with a boron cathode is of great interest for the production of advanced boron-based thin films. Cathodic arc is a technique employed to grow thin films at very high growth rates, compared to chemical vapor deposition and other physical deposition techniques. In the case of boron-based compounds this deposition can be to increase the wear resistance of a surface e.g., a cutting tool, and, under some conditions, substantially reduce its friction. In other cases the addition of boron can create special electrical properties in semiconductors, for example, silicon and silicon carbide.
The application of this technique to boron has been severely hampered by the poor performance of commercially available boron material for use as cathode due to serious degradation and to breakage during the arcing process.
It is thus an object of this invention to provide a novel process for forming a sintered boron cathode.
It is a further object of this invention to provide a boron cathode having longer lived operability under conditions of arcing.
It is a further yet more particular object of this invention to provide a unique boron structure not heretofore available in the prior art.
These as well as other objects are accomplished by binding together boron powders and subsequently heating the powders to remove binders and to subsequently sinter and densifiy the boron utilizing a microwave environment for so doing